# 7.打印1~20所有奇数的乘积
a = 1
chengji = 1
while a <= 20:
    if a % 2 != 0:  # 奇数不能被2整除
        chengji *= a
    a += 1
print("乘积为", chengji)
#第二种写法
while a <= 20:
    chengji *= a
    a += 2
